There have been recently diffused apparatuses that handle image information as digital and, at that time, for the purpose of highly-efficient information transmission and accumulation, employ a coding system for compression by orthogonal transformation and motion compensation such as discrete cosine transform with use of redundancy peculiar to the image information, to perform compression coding on images. Examples of this coding system include MPEG (Moving Picture Experts Group), H.264, and MPEG-4 Part10 (Advanced Video Coding, hereinafter described as AVC).
Now, for the purpose of higher improvement in coding efficiency than H.264/AVC, standardization of a coding system called HEVC (High Efficiency Video Coding) is being advanced by JCTVC (Joint Collaboration Team-Video Coding), which is a joint standardization organization formed by ITU-T (International Telecommunication Union Telecommunication Standardization Sector) and ISO/IEC (International Organization for Standardization/International Electrotechnical Commission).
Further, in HEVC, range extension (HEVC Range Extension) has been studied so as to support high-end formats, such as images in color difference signal formats like 4:2:2 and 4:4:4, profiles for screen content (see, for example, Non-Patent Literature 1).
Incidentally, Intra Block Copy (Intra BC) is a coding tool of performing a prediction by using a correlation within a screen and performing motion compensation within the screen. Intra BC is known as a tool that contributes to improvement in coding efficiency for artificial images such as computer screens and CG images.
However, the technique of Intra BC is not employed in the above-mentioned HEVC Range Extension extension and is continued to be studied for standardization of Screen Content Coding (SCC) extension (see, for example, Non-Patent Literature 2).
As of December 2014, in the standardization of the HEVC SCC extension, commonalizing Intra BC and inter coding is in discussion. In the case where Intra BC and inter coding are commonalized, it is necessary to communalize selection of a predicted vector (MV Predictor), transmission of an index (RefIdx) of a reference picture, transmission of a difference vector (MVD) between a current motion vector and a predicted vector, and the like.